1. Field of the Invention
The present invention relates to an extreme ultraviolet (EUV) light source apparatus to be used in combination with a processing unit for performing processing by using extreme ultraviolet light. For example, the present invention relates to an extreme ultraviolet light source apparatus to be used in combination with projection optics for performing exposure processing of semiconductor wafers in exposure equipment.
2. Description of a Related Art
In recent years, as semiconductor processes become finer, photolithography has been making rapid progress toward finer fabrication. In the next generation, microfabrication at 60 nm to 45 nm, further, microfabrication at 32 nm and beyond will be required. Accordingly, in order to fulfill the requirement for microfabrication at 32 nm and beyond, for example, exposure equipment is expected to be developed by combining an EUV light source for generating EUV light having a wavelength of about 13 nm and reduced projection reflective optics.
As the EUV light source, there are three kinds of light sources, which include an LPP (laser produced plasma) light source using plasma generated by irradiating a target with a laser beam, a DPP (discharge produced plasma) light source using plasma generated by discharge, and an SR (synchrotron radiation) light source using orbital radiation. The EUV light produced by the EUV light source is outputted to a processing unit for performing processing by using EUV light, for example, projection optics of exposure equipment.
As a related technology, United States Patent Application Publication US 2006/0146413 A1 discloses an EUV lithographic apparatus in which a radiation unit for radiating EUV light is arranged obliquely to the direction of gravitational force, and thereby, the EUV light is outputted in alignment with an optical axis of an illumination system for illuminating a mask by using the EUV light.
However, specifications of a numerical aperture (NA) and a position of an intermediate focusing point (IF) required for the EUV light source apparatus, an internal pressure necessary for the processing unit for performing processing by using the EUV light, and so on vary depending on the processing units. Accordingly, there is a problem that it may be necessary to change specifications of an EUV chamber according to the specifications of the processing units.